This invention relates to a route consideration apparatus selecting a plurality of probable routes where the vehicle is possibly to run and recognizing road geometry of the probable routes.
Currently, such navigators as having the following functions are practically used. Once a destination is designated by the driver, the navigator determines the shortest distance route and the shortest time route after calculations and shows those routes on the map in the display, while changing them depending on running of the vehicle and guiding the driver to those routes by outputting warnings.
Recently presented many times are such technologies as disclosed by the Japanese Patent Laid-open No. 194866/1996 for example, where a route consideration apparatus takes in the guided route inputted by the navigator, assigns it as the running route, and considers road geometry along with the running route (i.e., guided route) according to vehicle position and map data determined by or inputted from the navigator, then warnings are dispatched and vehicle speed is controlled in response to vehicle running conditions considering the recognized road geometry.
According to the prior arts aforementioned, road geometry is not considered in the cases that a guided route is not determined because the driver does not designate any destination or the vehicle is driven not along the guided route. Thus it becomes impossible to output warning against speed and control vehicle speed in response to road geometry in the front.
It can be thought that a route consideration apparatus considers all roads within a range in the front as probable routes and recognizes all their geometry, without taking in the guided route inputted from the navigator.
However, data quantity are too much for a route consideration apparatus to grasp geometry of all roads in the front and their branch roads because of the fact that a road, in general, has many intersections and branch roads. Thus, such an idea is impracticable.